Improvement of tribological properties of aluminum by nitrogen implantation

The present study reports on improvements of the tribomechanical properties of commercial aluminum especially wear and hardness by nitrogen implantation. The implantation process has been carried out at doses 5×1016, 1×1017 and 6×1017 ions/cm2 and energy 180 keV. The tribological tests for the friction coefficients and wear were made on a pin-on-disk tribotester with the load 0.98 N. XRD analyses were performed to obtain a characterization of the surface of the implanted sample. The implanted specimens were also annealed at 400 °C in addition to the non-implanted specimen for referring. The hardness showed remarkably significant improvement at the higher dose, 6×1017 ions/cm2. Before annealing, the friction coefficients of the implanted samples were nearly unchanged. After annealing at 400 °C, these coefficients exhibited a relative decrease from about 0.33-0.22 at dose 1×1017 ions/cm2. On the other hand, the wear rates of the implanted samples and the countersample exhibited a great decrease after annealing the samples of aluminum at 400 °C whereas the wear decreased from about 38 to 3 μm2 for the samples at the higher dose, 6×1017 ions/cm2.